Oil-in-water emulsions containing bitumen are used in numerous commercial applications such as road construction and repair, as well as in the construction industry as coatings and sealers. Bitumen-in-water emulsions are a specific type of oil-in-water emulsion in which the bitumen material exists as fine particles dispersed in a water phase. These emulsions possess numerous advantages over conventional bitumen compositions. Environmental advantages include reduction in fuel utilization and energy consumption because bitumen emulsions generally do not require hot storage and require hot application. Safety advantages exist because bitumen emulsions are generally water based and are not flammable. Bituminous emulsions also generally have greater versatility and performance than conventional asphalt and therefore can be used in a variety of applications and environmental conditions. There is a continuing need for improvements in bituminous emulsions, and for optimizing such compositions for various applications.
The asphalt properties of bituminous emulsions are obtained after the emulsions set or cure, when the droplets of bitumen coalesce and adhere to the substrate when water is removed. The rate of this setting process depends on the reactivity of the emulsion and the reactivity of the substrate. Emulsions are classified as rapid, medium and slow-setting types, depending on their reactivity. Emulsions can also be classified into cationic or anionic types depending on the charge on the bitumen droplets.
DE 19929962 is in the field of bituminous emulsions and relates to novel emulsifiers for the production of bitumen emulsions and the use of cation polymers as additives for the production of such preparations.
U.S. Pat. No. 3,871,893 relates to the use of lignin amines as surface active agents, especially in cationic asphalt emulsions.
In many cases, it is desirable to incorporate minerals (such as clay, silica or slate, for example) into bituminous emulsions so that the oil residue cured from the resulting emulsions behaves in the manner of nano-composites, which are generally more durable than non-modified residue. These minerals can be incorporated into bituminous emulsions either by initially utilizing mineral stabilized emulsions during formulation, by the post-addition of minerals or a mineral slurry into bituminous emulsions after the emulsions have been formed, or, alternatively, by the incorporation of bitumen materials which can include bitumen modifiers containing minerals. Advantageously, addition of minerals (especially clays) into bituminous emulsions naturally increases the viscosity and improves the storage ability of the resulting emulsions.
Due to the negative surface charge nature of minerals, anionic slow-setting emulsions (which are naturally compatible to minerals) are frequently utilized with mineral substances. Negatively charged minerals generally do not disrupt the negatively charged polar heads of the emulsifiers surrounding the bitumen particles in anionic emulsions. As a result, the addition of negatively charged minerals to anionic emulsions generally does not result in breakage of the emulsions.
The addition of negatively charged minerals to cationic emulsions is generally not possible because the negatively charged minerals can disrupt the positively charged polar heads of the emulsifiers surrounding the bitumen particles in cationic emulsions. As a result, the addition of negatively charged minerals to cationic emulsions frequently result in breakage of the emulsions.
For cationic slow-setting emulsions, quite high cationic emulsifier levels generally are needed for preparation of the cationic slow-setting emulsions, and the active ingredients in the cationic emulsifiers known in the art are generally mixtures of cationic emulsifiers with non-ionic emulsifiers. U.S. Pat. No. 3,539,368, describes incorporating negatively charged fillers in certain cationic emulsions by pretreatment of filler materials with tertiary amine oxides. WO2001000734 discloses the use of amidoamine emulsifiers.
For cationic rapid-setting emulsions, addition of negatively charged minerals is especially problematic. Excessive overdose of the cationic emulsifiers might make the cationic rapid-setting emulsions compatible to minerals, but the overdose of emulsifier will generally change the grade of the emulsions (from fast-setting to slow-setting type, for example).
In some limited cases, minerals or mineral slurries can be post-added into cationic emulsions to form short-stable mineral modified bitumen emulsions. This post-addition of minerals generally must occur after the emulsion has been created. There remains a need of directly formulating stable cationic emulsions with minerals. There is an ongoing need for improved cationic emulsion compositions that contain minerals (and the corresponding benefits of these minerals).
The compositions of the present disclosure increase the stability of cationic emulsions generally by increasing emulsion stability, increasing viscosity, and reducing emulsion particle size. The compositions of the present disclosure also address the problem of directly formulating stable cationic emulsions containing minerals and allows for the direct formulation of stable cationic emulsions, as well as more stable cationic emulsions containing post-added mineral slurries. These and other advantages of the present disclosure, as well as additional inventive features, will be apparent from the description of the inventions provided herein.